The long term objective of the research proposed here is to understand how growth, differentiation and patterning processes take place in vivo, using somatic stem cell proliferation in the Drosophila germarium (located at the tip of each ovariole) as a model system. Previous experiments have suggested a unique role for hedgehog (hh) in process. Therefore, to determine whether somatic cell proliferation in the germarium is absolutely dependent on hh and where its expression is necessary, the FLP- out technique will be used to generate null hh clones. To identify cells responsive to hh, marked clones of cells will be analyzed in wild-type versus hh--overexpressing germarium. In addition, two alternative approaches (a molecular or a genetic screen) are proposed to identify other genes involved in the control of somatic cell proliferation in the germarium. Further analysis of the potential role of the isolated genes in the control somatic cell proliferation will be initiated during the term of this fellowship and continued at a later stage. The use of this powerful genetic system to identify factor which control cell proliferation-differentiation in vivo and study their mechanisms of action will be valuable to understand how the disruption of such regulatory processes results in pathological conditions such as cancers and may provide insights into therapeutic strategies.